1. Field of the Invention
This invention relates to a method of preventing water leakage with a waterproof seal inserted in a clearance for connection between pipe and pipe to be used in the soil or under water or between sheet piles to be driven into the ground.
2. Prior Art
Methods of preventing water leakage by use of water-absorbing, expandable rubber (hereinafter called water-swelling rubber) are already known. They use the rubber, for example, as packings for water intake pipes and effluent pipes to be embedded in the ground or laid on the seabed, for flanged joints of pipings for water supply, Hume pipes, propelling pipes, and U-drains; and as segment seals for sheet piles and shields for structures. Such water-swelling rubber pieces absorb surrounding water and swell to volumes large enough to seal joints of piping and the like. Japanese Patent Application Kokoku Nos. 58-27435 and 58-27436 disclose waterproof seals of a structure consisting of a water-swelling rubber piece filled in a fabric tube which has a lower expansion rate but permits permeation of water to constrain the rubber expansion toward the contacting surfaces and allow the rubber to absorb water until it attains a sufficient leakproof pressure. Japanese Patent Application Kokai No. 6-249377 introduces a pipe joint structure using a packing of water-swelling rubber for the connection of water intake pipings installed under water and the like. It claims that the structure facilitates pipe joining work. Actually, however, it usually takes as long as about one week before such seals used with Hume pipes and the like in the soil or on the seabed absorb water to develop an adequate leakproof pressure (generally 2-20 kgf/cm.sup.2, preferably 5-6 kgf/cm.sup.2). This can retard the whole work, and the problem is how to shorten the above time period.
In an attempt to solve the problem, Japanese Patent Application Kokai No. 9-133272 reveals a method of obtaining an adequate leakproof pressure by use of a hollow seal packed with a synthetic resin or other filler material. It is not easy, however, to transport such filler material and filling equipment to the site of work and complete the seal on site. Therefore, a simpler approach to the problem has been sought.